Efficient workholding maximises new machine productivity

The use of state-of-the-art production technology, decades of in-depth experience and the application of stringent quality systems has resulted in the famous North East company gaining a reputation as a world leader in the field of bearing design and manufacture for both the industrial and the marine sectors.

As the efficiency, reliability and longevity of any bearing depends largely on the quality of the methods used its manufacture, Michell Bearings employs a wide range of CNC machine tools and advanced production aids at the company’s impressive South Shields, Tyne and Wear-based Headquarters.

The recent installation of a Hermle C60 UMT, 5 axis CNC machining centre prompted Chris Kemp, Michell Bearings’ manufacturing engineering manager to contact Tony Lewis of Thame Workholding with the intension of exploring efficient workholding ideas that would enable the company’s new acquisition to maximise its productive potential.

Mr Kemp explains: “As a leading designer and manufacturer of self-contained whitemetal bearings and also PTFE faced hydrodynamic bearings, our products can be found in a wide range of challenging applications throughout the world. In addition to countless industrial applications, Michell bearings provide high performance at sea. We have a long history of producing bearings that withstand the test of time and we have products installed with 35 of the world’s navies on more than 300 vessels.

“In accordance with our ongoing quest to enhance our capabilities and further increase our production efficiencies, we recently purchased a Hermle C60 UMT 5 axis CNC machining centre with a X, Y. Z capacities of 1,200mm, 1,300mm and 900mm. The new machine tool allows the dynamic processing of workpieces up to 2,000kg in weight.”

He continues: “With the aims of maximising its production potential, achieving the highest possible yield and also to help guarantee that the machine consistently meets our demanding standards of precision, I recently contacted Tony Lewis of Thame Workholding.

“We concluded that a workholding arrangement, incorporating Thame Workholding’s Lang QuickPoint system and Samchully jaw boxes, would be ideal for our needs. By working together, Tony and I developed the system incorporating Thame’s products that has considerably reduced our new machine tool’s set-up and job changeover times which has significantly increased its available production time. Secure workholding methods also help keep accuracy and surface finishes consistent.”

The workholding arrangement conceived consists of several circular ‘slave’ plates that can be set-up offline. The plates have Lang QuickPoint studs attached to their bases and a series of QuickPoint plates that remain loaded on the machine table. The slave plates also feature T-slots that allow Samchully jaw boxes to be moved into position, tightened onto the workpiece then centralised ready for loading onto the machine.

On completion of a machining routine, the slave plate holding the finished part can be removed by crane and the plate, holding the new workpiece, can be lowered into position. After securing the new plate to the machine’s table, the next machining operation can be immediately commenced.

It helps that the Hermle CNC machining centre’s spindle is able to move clear of the table, ensuring that the working area is completely unrestricted and accessible, allowing unhindered crane loading from directly above the machine table’s centre-line.

With high positional accuracy, the Lang QuickPoint system provides precise and repeatable mounting of fixtures and other elements on to machine tables, indexers, cubes, rotary tables and mill-turn machine tools. Thame says QuickPoint’s height of only 27mm makes it the lowest profile zero-point-system currently available. Manual clamping is achieved with just one tightening screw; alternatively, hydraulic or pneumatic clamping is also possible. The use of this simple and sturdy system allows a maximum pull-down force 6,000kg.

Mr Lewis concludes: “Our QuickPoint location system is a rapid and accurate clamping arrangement that offers a low profile of just 27mm. The system is based on four wedge bolts in the pallet that engage with four grooved locating bolts screwed to the vice or fixture. Clamping and unclamping is quickly performed by turning a central screw and repeatability is extremely accurate.

“The highly repeatable nature of QuickPoint guarantees that Michelle Bearings’ ‘slave’-plates, can be loaded with workpieces off-machine, then quickly and precisely attached to the Hermle machining centre’s table. Now, rather than wasting valuable time setting-up a workpiece when the machine is idle then performing a machining operation as consecutive activities, these processes are capable of being completed concurrently and within the machine’s cycle time. This method can help deliver outstanding machining efficiencies.”

Thame Workholding www.thameworkholding.com

Michell Bearings www.michellbearings.com